This invention relates to a method for welding an electrical lead wire to a terminal pin having a head with an internal opening, the electrical lead wire being received within the opening and having a portion extending to the exterior of the terminal-pin head. More particularly, the invention relates to a method for welding an electrical lead wire extending from the terminal pin of an exhaust gas sensor of the type having one or more ceramic, metal-oxide, oxygen-sensing elements supported by a ceramic insulator mounted in a steel body.
The steel body of the exhaust gas sensor is adapted to be positioned in an exhaust conduit through which flow exhaust gases from an internal combustion engine. The ceramic insulator supporting the oxygen-sensing element has one or more passages through each of which an electrical lead wire from the oxygen-sensing element passes for connection to a terminal pin mounted in the terminal-pin end of the exhaust gas sensor. The lead wire extends through an opening in the terminal-pin head and is welded to the terminal-pin head in accordance with the method of the invention. Prior to welding, the lead wire extends above the terminal-pin head.